In LTE (Long Term Evolution), when a mobile station UE in “RRC Connected state” moves across a cell boundary, a handover procedure is to take place in order to cause the mobile station UE to perform communication always by using an appropriate cell.
However, when the handover procedure takes place between cells using the same frequency, there is a concern that the mobile station UE cannot receive “HO command” from a handover source cell due to interference from a neighboring cell, and the handover procedure ends up in failure (see FIG. 5(a)).
Accordingly, as shown in FIG. 5(b), there has been proposed a control method (RRC diversity) for transmitting the “HO command” not only from the handover source cell but also from a handover destination cell in order to improve a probability of reception of the “HO command” by the mobile station UE, thus to suppress a failure in the handover procedure (see Non-patent Document 1).
Here, the “RRC diversity” can be implemented by CoMP transmission-reception (Coordinated Multi-Point transmission-reception) on a downlink.
Note that the CoMP transmission-reception on the downlink is a technique for improving throughput on the downlink by transmitting either the same or different data from multiple TPs (Transmission Points) to the mobile station UE.